多媒体编程ios摄像头图像抓取工具类

转载自  http://www.it165.net/pro/html/201408/19449.html

• 工具类提供预览图像画面，自动处理旋转，并且以主动方式抓取图像（这样帧率可以无限大）

  系统的接口多是异步接收图像，像我这种强迫症怎么受得了，必须吧被动接收图像的方式改成主动抓取。

  头文件

   

  view source print ?

  01. #import <Foundation/Foundation.h>

  02. #import <AVFoundation/AVFoundation.h>

  03.  

  04. //这些比例都是4：3的比例。

  05. typedef enum TKVideoFrameSize

  06. {

  07. tkVideoFrame480x360     = 480  << 16 | 360,

  08. tkVideoFrame720x540     = 720  << 16 | 540, //用这个分辨率，效率会快很多。

  09. }TKVideoFrameSize;

  10.  

  11.  

  12.  

  13. @interface TKVideoCapture : NSObject <AVCaptureVideoDataOutputSampleBufferDelegate>

  14.  

  15. - (bool) create:(UIView*)preview frame:(TKVideoFrameSize)type ;

  16. - (bool) destory;

  17.  

  18. - (bool) start ;

  19. - (bool) stop ;

  20.  

  21. //返回 字节顺序 BGRA BGRA 的图像数据。

  22. - (uint8_t*) get_image_rgb32:(uint32_t*)length ;

  23.  

  24. @end

   

  实现文件：（里面用到了那个Lock可以去上一篇文章找）

   

  view source print ?

  001. #import "TKVideoCapture.h"

  002. #import <UIKit/UIKit.h>

  003. #import <CoreGraphics/CoreGraphics.h>

  004. #import <CoreVideo/CoreVideo.h>

  005. #import <CoreMedia/CoreMedia.h>

  006. #import "TKLock.h"

  007.  

  008. @interface TKVideoCapture ()

  009. {

  010. TKVideoFrameSize            _frametype      ;

  011. UIView*                     _preview        ;

  012. AVCaptureSession*           _captureSession ;

  013. AVCaptureVideoPreviewLayer* _capturePreview ;

  014. AVCaptureVideoDataOutput *  _captureOutput  ;

  015. AVCaptureDevice*            _captureDevice  ;

  016. AVCaptureDeviceInput*       _captureInput   ;

  017.  

  018. uint8_t*                    _buffer_temp    ; //每一帧数据都存储到这个缓存中

  019. uint8_t*                    _buffer_obox    ; //需要使用时，从tempbuf 拷贝过来。

  020. CGRect                      _subImageRect   ; //子图片的位置。

  021.  

  022. TKLock*                     _buffer_lock    ;

  023. }

  024.  

  025. @end

  026.  

  027.  

  028. @implementation TKVideoCapture

  029.  

  030. - (void) do_create

  031. {

  032. self->_captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo] ;

  033. self->_captureInput  = [AVCaptureDeviceInput deviceInputWithDevice:self->_captureDevice  error:nil];

  034. self->_captureOutput = [[AVCaptureVideoDataOutput alloc] init];

  035.  

  036. if(self->_captureOutput)

  037. [self->_captureOutput setAlwaysDiscardsLateVideoFrames:true];

  038.  

  039. dispatch_queue_t queue = dispatch_queue_create("cameraQueue", NULL);

  040. [self->_captureOutput setSampleBufferDelegate:self queue:queue];

  041.  

  042. dispatch_release(queue);

  043.  

  044.  

  045. NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey;

  046. NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];

  047.  

  048. NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key];

  049.  

  050. [self->_captureOutput setVideoSettings:videoSettings];

  051. self->_captureSession = [[AVCaptureSession alloc] init];

  052.  

  053. uint16_t width  = (uint16_t)(((uint32_t)_frametype) >> 16) ;

  054. uint16_t height = (uint16_t)(((uint32_t)_frametype) & 0xFFFF) ;

  055.  

  056. _buffer_temp = (uint8_t*)malloc(width * height * 4);

  057. _buffer_obox = (uint8_t*)malloc(width * height * 4);

  058.  

  059. //0.75是预定比例

  060. switch (_frametype) {

  061. case tkVideoFrame480x360:

  062. {

  063. _captureSession.sessionPreset = AVCaptureSessionPreset640x480 ;

  064. _subImageRect = CGRectMake((640-360)/2, 0, 360, 480);

  065. break;

  066. }

  067. case tkVideoFrame720x540:

  068. {

  069. _captureSession.sessionPreset = AVCaptureSessionPresetiFrame1280x720 ;

  070. _subImageRect = CGRectMake((1280-540)/2, 0, 540, 720);

  071. break;

  072. }

  073. default:

  074. break;

  075. }

  076.  

  077. if(self->_captureInput != nil)

  078. [self->_captureSession addInput:self->_captureInput];

  079.  

  080. [self->_captureSession addOutput:self->_captureOutput];

  081.  

  082. self->_capturePreview = [AVCaptureVideoPreviewLayer layerWithSession: self->_captureSession];

  083. self->_capturePreview.frame = self->_preview.bounds;//CGRectMake(100, 0, 100, 100);

  084. self->_capturePreview.videoGravity = AVLayerVideoGravityResizeAspectFill;

  085. self->_capturePreview.connection.videoOrientation = [self getOrientation] ;

  086.  

  087. [self->_preview.layer addSublayer: self->_capturePreview];

  088.  

  089. _buffer_lock = [[TKLock alloc] init];

  090. [_buffer_lock open];

  091. }

  092.  

  093. - (bool) create:(UIView*)preview frame:(TKVideoFrameSize)type

  094. {

  095. self->_frametype     = type ;

  096. self->_preview       = preview ;

  097.  

  098. [self performSelectorOnMainThread:@selector(do_create) withObject:self waitUntilDone:true];

  099.  

  100. return true ;

  101. }

  102.  

  103. - (AVCaptureVideoOrientation) getOrientation

  104. {

  105. UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation ;

  106. switch(orientation)

  107. {

  108. case UIInterfaceOrientationPortrait: return AVCaptureVideoOrientationPortrait;

  109. case UIInterfaceOrientationPortraitUpsideDown: return AVCaptureVideoOrientationPortraitUpsideDown;

  110. case UIInterfaceOrientationLandscapeLeft: return AVCaptureVideoOrientationLandscapeLeft;

  111. case UIInterfaceOrientationLandscapeRight: return AVCaptureVideoOrientationLandscapeRight;

  112. }

  113. return AVCaptureVideoOrientationLandscapeLeft ;

  114. }

  115.  

  116. - (void) do_destory

  117. {

  118. [_buffer_lock close];

  119. [_buffer_lock release];

  120. _buffer_lock = nil ;

  121.  

  122. free(_buffer_temp);

  123. free(_buffer_obox);

  124. _buffer_temp = NULL ;

  125. _buffer_obox = NULL ;

  126.  

  127. [self->_captureSession stopRunning];

  128. [self->_capturePreview removeFromSuperlayer];

  129. [self->_captureOutput  release];

  130. [self->_captureSession release];

  131. self->_captureSession = nil ;

  132. self->_capturePreview = nil ;

  133. self->_captureOutput  = nil ;

  134. self->_captureDevice  = nil ;

  135. self->_captureInput   = nil ;

  136. self->_preview        = nil ;

  137. }

  138.  

  139. - (bool) destory

  140. {

  141. [self performSelectorOnMainThread:@selector(do_destory) withObject:self waitUntilDone:true];

  142. return true ;

  143. }

  144.  

  145. - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection

  146. {

  147. CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

  148. CVPixelBufferLockBaseAddress(imageBuffer,0);

  149. uint8_t* baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);

  150.  

  151. size_t width  = CVPixelBufferGetWidth(imageBuffer);

  152. size_t height = CVPixelBufferGetHeight(imageBuffer);

  153. size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);

  154.  

  155. CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

  156. CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, baseAddress, bytesPerRow * height, NULL);

  157.  

  158. CGImageRef imageRef = CGImageCreate(width, height, 8, 32, bytesPerRow, colorSpace,

  159. kCGBitmapByteOrder32Little|kCGImageAlphaPremultipliedFirst,

  160. provider, NULL, false, kCGRenderingIntentDefault);

  161.  

  162. CGImageRef subImageRef = CGImageCreateWithImageInRect(imageRef, _subImageRect);

  163.  

  164. size_t subWidth  = _subImageRect.size.height ;

  165. size_t subHeight = _subImageRect.size.width  ;

  166.  

  167. CGContextRef context = CGBitmapContextCreate(NULL, subWidth, subHeight,

  168. CGImageGetBitsPerComponent(subImageRef), 0,

  169. CGImageGetColorSpace(subImageRef),

  170. CGImageGetBitmapInfo(subImageRef));

  171.  

  172.  

  173. CGContextTranslateCTM(context, 0, subHeight);

  174. CGContextRotateCTM(context, -M_PI/2);

  175.  

  176. CGContextDrawImage(context, CGRectMake(0, 0, subHeight, subWidth), subImageRef);

  177.  

  178. uint8_t* data = (uint8_t*)CGBitmapContextGetData(context);

  179.  

  180. [_buffer_lock lock];

  181. memcpy(_buffer_temp, data, subWidth * subHeight * 4);

  182. [_buffer_lock unlock];

  183.  

  184. CGContextRelease(context);

  185. CGImageRelease(imageRef);

  186. CGImageRelease(subImageRef);

  187. CGDataProviderRelease(provider);

  188. CGColorSpaceRelease(colorSpace);

  189. CVPixelBufferUnlockBaseAddress(imageBuffer,0);

  190. }

  191.  

  192. - (void) do_start

  193. {

  194. [self->_captureSession startRunning];

  195. }

  196.  

  197. - (void) do_stop

  198. {

  199. [self->_captureSession stopRunning];

  200. }

  201.  

  202. - (bool) start

  203. {

  204. [self performSelectorOnMainThread:@selector(do_start) withObject:self waitUntilDone:true];

  205. return true ;

  206. }

  207. - (bool) stop

  208. {

  209. [self performSelectorOnMainThread:@selector(do_stop) withObject:self waitUntilDone:true];

  210. return true ;

  211. }

  212.  

  213. - (uint8_t*) get_image_rgb32:(uint32_t*)length

  214. {

  215. uint16_t width  = (uint16_t)(((uint32_t)_frametype) >> 16) ;

  216. uint16_t height = (uint16_t)(((uint32_t)_frametype) & 0xFFFF) ;

  217.  

  218. //从摄像头输出数据采集数据

  219. [_buffer_lock lock];

  220. memcpy(_buffer_obox, _buffer_temp, width * height * 4);

  221. [_buffer_lock unlock];

  222.  

  223. if(length)

  224. *length = width * height * 4 ;

  225.  

  226. return _buffer_obox ;

  227. }

  228.  

  229.  

  230. @end

   

延伸阅读：

• 1、IOS关于从照相机获取图片的问题 初步探究通过摄像头实现颜色与形状识别机制
• 2、iOS摄像头和相册UIImagePickerController浅析
• 3、IOS应用程序 图像浏览及音频播放
• 4、关于iOS中显示WEBP图像的学习记录
• 5、iOS使用CoreImage处理图像40中可用的滤镜名称
• 6、多媒体编程ios视频图像绘制工具类。
• 7、IOS利用AVPlayer开发多媒体在线播放器
• 8、全能多媒体开发框架Vitamio

 

转载于:https://www.cnblogs.com/allanliu/p/4203518.html